Modern helicopters have complex, coupled boundaries of operation, which the pilot is required to monitor. Proximity to power limits associated with the engine and transmission are particularly critical for cargo-class helicopters with low power margin conditions in effect. Pilot monitoring of power limits leads to significantly increased workload and failure to successfully monitor power can lead to rotor droop as well as additional fatigue damage.
Research has enumerated a comprehensive set of helicopter limits, including power limits, and studies have been conducted to identify effective methods to cue the pilot to these limits. These studies have determined that heads-up methods, such as tactile cues, were more effective at alerting the pilot in a high-bandwidth manor.
Further work has defined the concept and benefits of carefree maneuvering as well and additional studies have been conducted on tactile cueing of torque limits. Some of these studies determined that predictive algorithms were important for effective power limit tactile cueing and developed advanced algorithms for this purpose. However, where a flying power limit cueing system has been developed, the system does not combine all limits into equivalent torque limits, nor does it reflect real-time variations in all engine performance parameters.